ABCB1 and neoplasm: To rule out any artefact due to inter-individual variation in ABCB1, FOXC1, PTEN and PPP2R2B methylation patterns in normal tissue and to confirm the presence of DNA methylation to be a tumour specific event, we analyzed the methylation patterns in 23 additional normal tissues without histopathological findings, confirming the initial findings of an absence of DNA methylation around the transcription start site of these genes in normal breast tissue (Figures 2 and 3A).